Adding sulphur to wine

Sulphur dioxide (SO2) is the most widely used and controversial additive in winemaking. Its main functions are to inhibit or kill unwanted yeasts and bacteria, and to protect wine from oxidation.

SO2 is added at several points in the process of conventional vinification and is present in the finished wine in the form of sulphites (sulfites, if you're American).

Sulphites occur naturally in all living things and are present in small quantities even in unsulphured wines. They can cause potentially fatal allergic reactions.

Sulphur dioxide should not be confused with the powdered sulphur which is sometimes dusted onto vines to protect them from powdery mildew (called oidium in French), even in organic viticulture.

Downy mildew can be controlled effectively with herbal treatments.


It is often claimed that the Romans used sulphur to preserve their wines, but the evidence for this is vague.

The first explicit mention of its use in winemaking is a German royal decree of 1487. This permitted winemakers to burn sulphured woodchips in barrels used for storing wine.

This is an effective method of disinfection and is still a common practice (using pure powdered sulphur rather than woodchips) although steam-cleaning is now an alternative.

The systematic use of sulphur dioxide to control fermentation and to stabilise the wine at bottling was perfected by the French in North Africa early in the twentieth century.

It was a way of making wine in conditions that were essentially too hot. This approach quickly caught on in other climates, as a way of making wine without having to worry about it.

Unsulphured wines

Most winemakers will tell you that it is not possible to make good wine without sulphur dioxide. This is not true.

But the risks are such that very few winemakers are prepared to take them. supports unsulphured wines. We admire winemakers with the skill and courage to make them, and we want to give them the publicity they deserve.

The myth that sulphur dioxide is always necessary needs to be fought.

But we also recognise that in certain circumstances sulphur dioxide is the only option.

Used at bottling in homeopathic doses it does little or no damage to the flavour of the wine, and can help to protect it from being mishandled.

There are some very natural winemakers who work in this way.